Lassa fever is a viral infection similar to other hemorrhagic fever viruses like Ebola and Marburg, but it’s not as contagious or deadly as Ebola. It’s caused by the Mastomys rat, which is common in West Africa. The virus spreads to humans through contact with the rat’s feces or urine. Health workers can get infected through direct contact with an infected patient’s bodily fluids, making the outbreak season, typically between December and June, especially challenging for them. In 2018, Nigeria faced a significant outbreak of Lassa fever.
This disease can be fatal as it may lead to multiple organ failures, including the kidneys, liver, or spleen. Although it’s a hemorrhagic fever, most people infected with the virus don’t show symptoms. Annually, between 100,000 to 300,000 cases occur in West Africa, with about 5,000 resulting in death. In certain regions of Liberia and Sierra Leone, Lassa fever accounts for up to 16% of hospitalizations. The virus poses a risk of spreading internationally, as seen in a 2015 case where a traveler from Liberia was diagnosed with Lassa fever in the U.S.
Lassa fever was first identified in Nigeria in 1969 and is named after the village where it was discovered. It is prevalent in countries like Guinea, Nigeria, Liberia, and Sierra Leone, where the Mastomys rat is also common. Although Lassa fever is contagious, it’s not as easily spread as the Ebola virus. It can transfer from human to human through bodily fluids, but casual contact typically doesn’t spread it. Health and laboratory workers are at risk if they don’t take proper precautions, and patients can spread the virus through reused needles in poorly equipped hospitals.
Symptoms of Lassa fever often appear within 6 to 21 days of infection. While many people show no symptoms, others may experience headaches, fever, and general discomfort. Severe symptoms include difficulty breathing, bleeding, vomiting, and swollen airways. The disease can also cause hearing loss, heart complications, and brain inflammation. About 20% of infected individuals develop severe symptoms, and approximately 1% of cases are fatal, usually due to multiple organ failures within two weeks of symptom onset.
Hearing loss is a common complication, affecting 20-30% of patients, and can result in permanent deafness. Pregnant women in their third trimester have a high risk of complications, often leading to spontaneous pregnancy loss.
Diagnosis of Lassa fever is difficult due to its varied symptoms, which are similar to other viral hemorrhagic fevers like Ebola, typhoid, and malaria. Reliable diagnosis requires specialized laboratory tests, including Enzyme-linked Immunosorbent Serologic Assays (ELISA) and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR), though RT-PCR is mainly used for research purposes.
Early treatment with the antiviral drug Ribavirin can significantly reduce mortality rates, though it can cause side effects like hemolytic anemia. The availability of Ribavirin is limited, and there is no vaccine currently available, though research is ongoing.
Preventing outbreaks of Lassa fever focuses on community hygiene to control the rat population. Key prevention measures include frequent hand washing, keeping homes clean, storing food in rodent-proof containers, and using safe practices when caring for sick family members. Healthcare workers should use protective gear and follow strict infection control practices. Despite efforts, completely eradicating the Mastomys rat is challenging, but ongoing awareness and improved treatment methods help manage the disease.